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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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A nonporous membrane based on the polymerization of 2,3-dihydrofuran followed by crosslinking in situ was prepared. The material is compatible with rechargeable Li battery components and, when swollen with an appropriate solvent such as tetrahydrofuran, exhibits separator resistance and Li transport equivalent to Celgard.
Data for the system n-pentane/n-heptane on porous Chromosorb-102 adsorbent were obtained at 150, 175, and 200 C for mixtures containing zero to 100% n-pentane by weight. Prior results showing limitations on superposition of pure component data to predict multicomponent chromatograms were verified. The thermodynamic parameter MR0 was found to be a linear function of sample composition. A nonporous adsorbent failed to separate the system because of large input sample dispersions. A proposed automated data processing scheme involving magnetic tape recording of the detector signals and processing by a minicomputer was rejected because of resolution limitations of the available a/d converters. Preliminary data on porosity and pore size distributions of the adsorbents were obtained.
Dispersion /peak broadening/ in gel chromatography measured with nonporous and porous column packings, suggesting diffusion controlled separation with linear permeation isotherm
Phenolic resins are an important component of many ablative heat shield materials, which protect spacecrafts from the extreme temperatures reached during atmospheric entry. Examples include the high-density Heritage Carbon Phenolic (HCP) used in the Pioneer-Venus and Galileo missions, as well as the low-density Phenolic Impregnated Carbon Ablator (PICA) used in the Mars Science Laboratory and Mars 2020 missions. Additionally, recent developments within NASA have produced the mid-density Heatshield for Extreme Entry Environment Technology (HEEET) and its derivative 3D Woven Mid-Density Carbon Phenolic (3MDCP). Unlike the nonporous phenolic in HCP, PICA and HEEET/3MDCP are fabricated by infusing preforms with diluted phenolic formulations to obtain a lower density porous matrix. Despite the importance of the phenolic phase to the material response during entry, the variation in properties of porous and nonporous phenolic is not well understood. Here, we present an investigation of porous and nonporous phenolic resins using molecular dynamics (MD) simulations. Resin cure is mimicked in the simulations through the inclusion of representative reaction templates to generate accurate models of the complex crosslinked structures. To create porous models, explicit solvent molecules are included during the cure simulations. We observe nanoscale separation of the phenolic and solvent phases, which results in significant differences in the final structures of porous and nonporous models. In addition to a quantitative assessment of the network structure and porosity, we elucidate the effects of the phenolic formulation on the final material properties. These results are compared with experimental data as appropriate.
Operation of aerobic biological reactors in space is controlled by a number of challenging constraints, mainly stemming from mass transfer limitations and phase separation. Immobilized-cell packed-bed bioreactors, specially designed to function in the absence of gravity, offer a viable solution for the treatment of gray water generated in space stations and spacecrafts. A novel gravity-independent wastewater biological processor, capable of carbon oxidation and nitrification of high-strength aqueous waste streams, is presented. The system, consisting of a fully saturated pressurized packed bed and a membrane oxygenation module attached to an external recirculation loop, operated continuously for over one year. The system attained high carbon oxidation efficiencies often exceeding 90% and ammonia oxidation reaching approximately 60%. The oxygen supply module relies on hydrophobic, nonporous, oxygen selective membranes, in a shell and tube configuration, for transferring oxygen to the packed bed, while keeping the gaseous and liquid phases separated. This reactor configuration and operating mode render the system gravity-independent and suitable for space applications.